Malaria species positivity rates among symptomatic individuals across regions of differing transmission intensities in Mainland Tanzania.

Recent data indicate that non- species may be more prevalent than previously realized in sub-Saharan Africa, the region where 95% of the world's malaria cases occur. Although spp., and are generally less severe than , treatment and control are more challenging, and their geographic distributions are not well characterized. In order to characterize the distribution of malaria species in Mainland Tanzania (which has a high burden and geographically heterogeneous transmission levels), we randomly selected 3,284 samples from 12,845 samples to determine presence and parasitemia of different malaria species. The samples were collected from cross-sectional surveys in 100 health facilities across ten regions and analyzed via quantitative real-time PCR to characterize regional positivity rates for each species. was most prevalent, but and were found in all regions except Dar es Salaam, with high levels (>5%) of in seven regions (70%). The highest positivity rate of was 4.5% in Mara region and eight regions (80%) had positivity rates ≥1%. We also detected three infections in the very low-transmission Kilimanjaro region. While most samples that tested positive for non-falciparum malaria were co-infected with , 23.6% (n = 13/55) of and 14.7% (n = 24/163) of spp. samples were mono-infections. remains by far the largest threat, but our data indicate that malaria elimination efforts in Tanzania will require increased surveillance and improved understanding of the biology of non-falciparum species.